U.S. patent application number 17/495014 was filed with the patent office on 2022-01-27 for robotic cutting systems and methods for surgical saw blade cutting on hard tissue.
This patent application is currently assigned to MAKO Surgical Corp.. The applicant listed for this patent is MAKO Surgical Corp.. Invention is credited to David Gene Bowling, Seamus Gilhooley, Paul Shiels.
Application Number | 20220022986 17/495014 |
Document ID | / |
Family ID | |
Filed Date | 2022-01-27 |
United States Patent
Application |
20220022986 |
Kind Code |
A1 |
Gilhooley; Seamus ; et
al. |
January 27, 2022 |
Robotic Cutting Systems And Methods For Surgical Saw Blade Cutting
On Hard Tissue
Abstract
Methods of cutting bone using a robotic cutting system are
provided. The robotic cutting system includes one or more
controllers, a robotic manipulator, and one or more cutting tools,
such as those including a bur or a saw blade, that can be coupled
to the robotic manipulator. An initial cut, such as a notch, is
made into the bone with the bur or the saw blade. This notch is
then used to constrain the saw blade for limiting skiving of the
saw blade during cutting along a cutting plane.
Inventors: |
Gilhooley; Seamus; (Athenry,
IE) ; Bowling; David Gene; (Los Ranchos De
Albuquerque, NM) ; Shiels; Paul; (Albuquerque,
NM) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MAKO Surgical Corp. |
Weston |
FL |
US |
|
|
Assignee: |
MAKO Surgical Corp.
Weston
FL
|
Appl. No.: |
17/495014 |
Filed: |
October 6, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16131400 |
Sep 14, 2018 |
11166775 |
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17495014 |
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62559096 |
Sep 15, 2017 |
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International
Class: |
A61B 34/00 20060101
A61B034/00; A61B 34/32 20060101 A61B034/32; A61B 34/30 20060101
A61B034/30; A61B 17/14 20060101 A61B017/14; A61B 17/15 20060101
A61B017/15 |
Claims
1. A method of cutting bone using a robotic cutting system
including a robotic manipulator, a cutting tool coupled to the
robotic manipulator and having a saw blade configured to cut a
bone, and one or more controllers coupled to the robotic
manipulator, the method comprising: controlling, with the one or
more controllers, the robotic manipulator and the cutting tool to
facilitate cutting along an initial plane with the saw blade to
create a notch; controlling, with the one or more controllers, the
robotic manipulator and the cutting tool to facilitate reorienting
the saw blade from the initial plane to a cutting plane that is at
a different orientation than the initial plane; and controlling,
with the one or more controllers, the robotic manipulator and the
cutting tool to facilitate cutting along the cutting plane with the
saw blade and capturing the saw blade with the notch created along
the initial plane for limiting skiving of the saw blade during
cutting along the cutting plane.
2. The method of claim 1, wherein controlling the robotic
manipulator and the cutting tool to facilitate reorienting the saw
blade from the initial plane to the cutting plane further occurs
while the saw blade is located in the notch.
3. The method of claim 1, wherein controlling the robotic
manipulator and the cutting tool to facilitate reorienting the saw
blade from the initial plane to the cutting plane further occurs
while the saw blade is oscillating.
4. The method of claim 1, wherein controlling the robotic
manipulator and the cutting tool to facilitate cutting along the
initial plane with the saw blade to create the notch further
comprises the one or more controllers constraining movement of the
saw blade using a first virtual boundary defining the initial
plane.
5. The method of claim 4, wherein the cutting plane is defined by a
second virtual boundary, different than the first virtual boundary,
further comprising the one or more controllers deactivating the
first virtual boundary after creating the notch.
6. The method of claim 1, wherein controlling the robotic
manipulator and the cutting tool to facilitate cutting along the
initial plane with the saw blade to create the notch further
comprises the one or more controllers performing at least one of:
autonomously moving the cutting tool; and constraining movement of
the cutting tool.
7. The method of claim 1, wherein controlling the robotic
manipulator and the cutting tool to facilitate reorienting the saw
blade from the initial plane to the cutting plane further comprises
the one or more controllers performing at least one of:
autonomously moving the cutting tool; and constraining movement of
the cutting tool.
8. The method of claim 1, further comprising the one or more
controllers controlling the robotic manipulator for autonomously
aligning the saw blade with the initial plane.
9. The method of claim 1, wherein the initial plane is defined as
being normal to an outer surface of the bone.
10. A method of cutting bone using a robotic cutting system
including a robotic manipulator, a first cutting tool configured to
be coupled to the robotic manipulator and comprising a bur, a
second cutting tool configured to be coupled to the robotic
manipulator and having a saw blade configured to cut a bone along a
cutting plane, and one or more controllers coupled to the robotic
manipulator, the method comprising: controlling, with the one or
more controllers, the robotic manipulator and the first cutting
tool to facilitate burring a notch into the bone with the bur; and
controlling, with the one or more controllers, the robotic
manipulator and the second cutting tool to facilitate cutting along
the cutting plane with the saw blade and capturing the saw blade
with the notch burred into the bone for limiting skiving of the saw
blade during cutting along the cutting plane.
11. The method of claim 10, wherein controlling the robotic
manipulator and the first cutting tool to facilitate burring the
notch into the bone further comprises the one or more controllers
constraining movement of the bur using a first virtual
boundary.
12. The method of claim 11, wherein the cutting plane is defined by
a second virtual boundary, different than the first virtual
boundary, and further comprising the one or more controllers
deactivating the first virtual boundary after burring the
notch.
13. The method of claim 10, wherein controlling the robotic
manipulator and the first cutting tool to facilitate burring the
notch into the bone further comprises the one or more controllers
performing at least one of: autonomously moving the bur; and
constraining movement of the bur.
14. The method of claim 10, wherein controlling the robotic
manipulator and the second cutting tool to facilitate cutting along
the cutting plane further comprises the one or more controllers
performing at least one of: autonomously moving the saw blade; and
constraining movement of the saw blade.
15. The method of claim 10, wherein controlling the robotic
manipulator and the first cutting tool to facilitate burring the
notch into the bone further comprises the one or more controllers
controlling the robotic manipulator and the first cutting tool to
facilitate burring about an axis perpendicular to cutting
plane.
16. The method of claim 10, wherein: controlling the robotic
manipulator and the first cutting tool to facilitate burring the
notch occurs while the second cutting tool is coupled to the
robotic manipulator; and controlling the robotic manipulator and
the second cutting tool to facilitate cutting along the cutting
plane occurs while the first cutting tool is coupled to the robotic
manipulator.
17. The method of claim 10, wherein: controlling the robotic
manipulator and the first cutting tool to facilitate burring the
notch occurs while the second cutting tool is uncoupled from the
robotic manipulator; and controlling the robotic manipulator and
the second cutting tool to facilitate cutting along the cutting
plane occurs while the first cutting tool is uncoupled from the
robotic manipulator.
18. The method of claim 10, further comprising the one or more
controllers obtaining a predetermined position and orientation of
the cutting plane based on an implant and a 3D model of the
bone.
19. A method of operating a robotic cutting system, the robotic
cutting system comprising a robotic manipulator, a cutting tool
configured to be coupled to the robotic manipulator and having a
saw blade for cutting a bone, and one or more controllers coupled
to the robotic manipulator, the method comprising the one or more
controllers controlling the robotic manipulator for: aligning the
saw blade along a first plane; operating the cutting tool for
creating a groove in the bone with the saw blade along the first
plane; reorienting the saw blade along a second plane that
virtually intersects the first plane within a volume of the bone;
and operating the cutting tool for cutting the bone with the saw
blade along the second plane whereby the saw blade crosses into the
groove during cutting along the second plane for limiting skiving
of the saw blade.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The subject patent application is a Divisional of U.S.
Nonprovisional patent application Ser. No. 16/131,400, filed on
Sep. 14, 2018, which claims the benefit of and priority to U.S.
Provisional Patent Application No. 62/559,096, filed on Sep. 15,
2017, the disclosures of which are both hereby incorporated herein
by reference.
TECHNICAL FIELD
[0002] The embodiments described herein generally relate to robotic
cutting systems and methods of use thereof.
BACKGROUND
[0003] It is prevalent to use powered surgical saws during surgical
procedures. Generally, these surgical saws may be operated by a
user such as a surgeon or may be operated by a robotic cutting
system. The surgical saws include a saw blade which is configured
to cut hard tissue of a patient, such as bone. For example, saw
blades are used in total knee arthroplasty, total hip arthroplasty,
and similar types of procedures to create planar cuts on the
bone.
[0004] In conventional surgical saws, undesirable skiving (e.g.,
deviation from an intended cut plane and/or deviation from an
intended entry point) occurs during the cutting process, and
specifically during the initial cut of the hard tissue with the saw
blade. Skiving can be particularly difficult to control when making
an initial cut on non-flat portions of hard tissue, such as at the
ends of a femur (e.g., condyles, femur head). Skiving often
includes undesirable flexing of the saw blade away from the desired
location of the initial cut. One option to reduce skiving is to
employ a cutting guide for the saw blade to hold the saw blade in
place while making the necessary cuts. However, using cutting
guides can increase the length of time it takes to make the
necessary cuts because it requires that the cutting guide first be
secured to the bone at the desired location. Additionally, the use
of cutting guides often require the use of longer blades, which can
still introduce skiving effects. In robotic surgery, one of the
goals is to increase cutting accuracy and reduce cutting time,
which can be difficult in cases where the saw blade is unable to
initially cut at a desired location.
[0005] A robotic cutting system for controlling a surgical saw in a
manner that overcomes one or more of the aforementioned challenges
is desired.
SUMMARY
[0006] In one embodiment, a robotic cutting system is provided. The
robotic cutting system comprises a robotic manipulator and a
cutting tool to be coupled to the robotic manipulator. The cutting
tool has a blade configured to cut a bone along a cutting plane. A
controller is coupled to the robotic manipulator to control the
robotic manipulator and the cutting tool to perform an initial
stage of cutting along an initial plane prior to performing a final
stage of cutting along the cutting plane. The initial plane is at a
different orientation than the cutting plane. The controller is
configured to control the robotic manipulator and the cutting tool
to facilitate cutting along the initial plane with the blade to
create a notch for the blade and to facilitate reorienting the
blade from the initial plane to the cutting plane.
[0007] In another embodiment, a robotic cutting system is provided.
The robotic cutting system comprises a robotic manipulator and a
cutting tool to be coupled to the robotic manipulator. The cutting
tool has a blade configured to cut a bone along a cutting plane. A
controller is coupled to the robotic manipulator to control the
robotic manipulator to reciprocate the blade along the cutting
plane to create a notch for the blade prior to resecting the bone
along the cutting plane. In another embodiment, a robotic cutting
system is provided. The robotic cutting system comprises a robotic
manipulator and a cutting tool to be coupled to the robotic
manipulator. The cutting tool has a blade configured to cut a bone
along a cutting plane. The robotic cutting system also comprises a
bur to be coupled to the robotic manipulator. A controller is
coupled to the robotic manipulator to control the robotic
manipulator to perform an initial stage of burring a notch into the
bone for the blade prior to performing a final stage of cutting
along the cutting plane with the blade.
[0008] In another embodiment, a robotic cutting system is provided.
The robotic cutting system comprises a robotic manipulator and a
cutting tool to be coupled to the robotic manipulator. The cutting
tool has a blade configured to cut a bone along a cutting plane. A
controller is coupled to the robotic manipulator to control the
robotic manipulator to perform cutting along the cutting plane. A
blade guide is coupled to the robotic manipulator. The controller
is configured to control the robotic manipulator and the cutting
tool to facilitate cutting along the cutting plane while guiding
the blade with the blade guide. The blade guide is capable of
retracting as the blade penetrates into the bone along the cutting
plane.
[0009] A method of cutting bone using a robotic cutting system is
also provided. The method comprises controlling a robotic
manipulator and a cutting tool to facilitate cutting along an
initial plane with a blade to create a notch for the blade and to
facilitate reorienting the blade from the initial plane to a
cutting plane, the initial plane being at a different orientation
than the cutting plane.
[0010] Another method of cutting bone using a robotic cutting
system is provided. The method comprises controlling a robotic
manipulator to reciprocate a blade along a cutting plane to create
a notch for the blade prior to the bone being resected along the
cutting plane.
[0011] Another method of cutting bone using a robotic cutting
system is provided. The method comprises controlling a robotic
manipulator to burr a notch into the bone for receiving a blade
prior to resecting the bone along a cutting plane with the
blade.
[0012] Another method of cutting bone using a robotic cutting
system is provided. The method comprises controlling a robotic
manipulator and a cutting tool to facilitate cutting along a
cutting plane while guiding a blade with a retractable blade guide
retracting the blade guard as the blade penetrates into the bone
along the cutting plane.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Advantages of the present disclosure will be readily
appreciated as the same becomes better understood by reference to
the following detailed description when considered in connection
with the accompanying drawings wherein:
[0014] FIG. 1 is a perspective view of a robotic cutting system in
an operating room;
[0015] FIG. 2 is a perspective view of the robotic cutting
system;
[0016] FIG. 3A is a side view of a cutting tool of the robotic
cutting system according to one embodiment in a first
orientation;
[0017] FIG. 3B is a side view of the cutting tool of the robotic
cutting system according to one embodiment in a second
orientation;
[0018] FIG. 4 is a side view of the cutting tool of the robotic
cutting system according to another embodiment;
[0019] FIG. 5A is a side view of the cutting tool of the robotic
cutting system according to yet another embodiment;
[0020] FIG. 5B is a side view of a blade of the robotic cutting
system according to the embodiment illustrated in FIG. 5A;
[0021] FIG. 6A is a side view of the cutting tool of the robotic
cutting system according to yet another embodiment in the first
orientation;
[0022] FIG. 6B is a side view of the cutting tool of the robotic
cutting system according to the embodiment illustrated in FIG. 6A
in the second orientation;
[0023] FIG. 7A is a side view of the cutting tool of the robotic
cutting system having a blade guide in an extended position;
and
[0024] FIG. 7B is a side view of the cutting tool of the robotic
cutting system having the blade guide in a retracted position.
[0025] FIG. 7C is a perspective view of the blade guide
illustrating the blade guide defining a passage being wider than a
saw blade to allow oscillations of the saw blade in the
passage.
DETAILED DESCRIPTION
[0026] Referring to the Figures, a robotic cutting system 10 is
shown for use during surgical procedures. The surgical procedures
may be orthopedic surgeries, brain surgeries, or any other
surgeries requiring the use of a cutting instrument. Typically, the
surgical procedure will include the cutting of hard tissue 12, such
as bone or the like. In some embodiments, the surgical procedure
involves partial or total knee, hip, or shoulder replacement
surgery, or may involve spine surgery.
[0027] The robotic cutting system 10 is designed to cut away
material. In some cases, the material (e.g., bone) is to be
replaced by surgical implants such as hip, knee, shoulder, and
spine implants, including unicompartmental, bicompartmental, or
total knee implants, acetabular cups, femur stems, humerus
implants, and the like. Some of these types of implants are
disclosed in U.S. Patent Application Publication No. 2012/0330429,
entitled, "Prosthetic Implant and Method of Implantation," the
entire disclosure of which is hereby expressly incorporated by
reference herein. It should be appreciated that the systems and
methods disclosed herein may be used to perform other procedures,
surgical or non-surgical, or may be used in industrial applications
or other applications.
[0028] The robotic cutting system 10 comprises a navigation system
13 including a localizer 14 and tracking devices 16, one or more
displays 18, and a robotic manipulator comprising a robotic arm 20
and a base 22. The robotic arm 20 includes a base link 24 rotatably
coupled to the base 22 and a plurality of arm links 26 serially
extending from the base link 24 to a distal end 28. The arm links
26 pivot/rotate about a plurality of joints in the robotic arm 20.
A cutting tool 30 is connected to the distal end 28 of the robotic
arm 20. The robotic arm 20 may be capable of moving the cutting
tool 30 in multiple degrees of freedom, e.g., five or six degrees
of freedom.
[0029] A robotic controller 32 is coupled to the robotic
manipulator to provide control of the robotic arm 20 or guidance to
the surgeon during manipulation of the cutting tool 30. In one
embodiment, the robotic controller 32 is configured to control the
robotic arm 20 (e.g., joint motors thereof) to provide haptic
feedback to the user via the robotic arm 20. This haptic feedback
helps to constrain or inhibit the surgeon from manually
manipulating (e.g., moving) the cutting tool 30 beyond predefined
virtual boundaries associated with the surgical procedure. Such a
haptic feedback system and associated haptic objects that define
the virtual boundaries are described, for example, in U.S. Pat. No.
8,010,180, which is hereby incorporated by reference herein in its
entirety. In one embodiment, the robotic cutting system 10
comprises the RIO.TM. Robotic Arm Interactive Orthopedic System
manufactured by MAKO Surgical Corp. of Fort Lauderdale, Fla.,
USA.
[0030] In some embodiments, the robotic arm 20 acts autonomously
based on predefined tool paths and/or other predefined movements to
perform the surgical procedure. Such movements may be defined
during the surgical procedure and/or before the procedure. In
further embodiments, a combination of manual and autonomous control
is utilized. For example, a robotic system that employs both a
manual mode in which a user manipulates the cutting tool 30 by
applying force to the cutting tool 30 to cause movement of the
robotic arm 20 and a semi-autonomous mode in which the user holds a
pendant to control the robotic arm 20 to autonomously follow a tool
path is described in U.S. Pat. No. 9,566,122, hereby incorporated
by reference herein in its entirety.
[0031] The navigation system 13 is set up to track movement of
various objects in the operating room. Such objects include, for
example, the cutting tool 30, the patient's anatomy of interest,
e.g., the femur F and tibia T, and/or other objects. The navigation
system 13 tracks these objects for purposes of displaying their
relative positions and orientations to the surgeon and, in some
cases, for purposes of controlling or constraining manual
manipulation of the cutting tool 30 relative to virtual boundaries
associated with the patient's anatomy.
[0032] The navigation system 13 includes a cart assembly 34 that
houses a navigation controller 36. The navigation controller 36 and
the robotic controller 32 collectively form a control system of the
robotic cutting system 10. A navigation interface is in operative
communication with the navigation controller 36. The navigation
interface includes the displays 18 that are adjustably mounted to
the cart assembly 34. Input devices such as a keyboard and mouse
can be used to input information into the navigation controller 36
or otherwise select/control certain aspects of the navigation
controller 36. Other input devices are contemplated including a
touch screen (not shown) or voice-activation.
[0033] The localizer 14 communicates with the navigation controller
36. In the embodiment shown, the localizer 14 is an optical
localizer and includes a camera unit (one example of a sensing
device). The camera unit has an outer casing that houses one or
more optical position sensors. In some embodiments at least two
optical sensors are employed, sometimes three or more. The optical
sensors may be separate charge-coupled devices (CCD). The camera
unit is mounted on an adjustable arm to position the optical
sensors with a field of view of the below discussed tracking
devices 16 that, ideally, is free from obstructions. In some
embodiments the camera unit is adjustable in at least one degree of
freedom by rotating about a rotational joint. In other embodiments,
the camera unit is adjustable about two or more degrees of
freedom.
[0034] The localizer 14 includes a localizer controller (not shown)
in communication with the optical sensors to receive signals from
the optical sensors. The localizer controller communicates with the
navigation controller 36 through either a wired or wireless
connection (not shown). One such connection may be an IEEE 1394
interface, which is a serial bus interface standard for high-speed
communications and isochronous real-time data transfer. The
connection could also use a company specific protocol. In other
embodiments, the optical sensors communicate directly with the
navigation controller 36.
[0035] Position and orientation signals and/or data are transmitted
to the navigation controller 36 for purposes of tracking the
objects. The cart assembly 34, the displays 18, and the localizer
14 may be like those described in U.S. Pat. No. 7,725,162 to
Malackowski, et al. issued on May 25, 2010, entitled "Surgery
System," hereby incorporated by reference.
[0036] The navigation controller 36 can be a personal computer or
laptop computer, or any other suitable form of controller.
Navigation controller 36 has the displays 18, central processing
unit (CPU) and/or other processors, memory (not shown), and storage
(not shown). The navigation processors can be any type of
processor, microprocessor or multi-processor system. The navigation
controller 36 is loaded with software as described below. The
software converts the signals received from the localizer 14 into
data representative of the position and orientation of the objects
being tracked.
[0037] Navigation system 13 includes the plurality of tracking
devices 16, also referred to herein as trackers. In the illustrated
embodiment, trackers 16 are coupled to separate bones of the
patient, e.g., the femur F and tibia T. In some cases, the trackers
16 are firmly affixed to sections of bone via bone screws, bone
pins, or the like. In other cases, clamps on the bone may be used
to attach the trackers 16. In further embodiments, the trackers 16
could be mounted to other tissue types or parts of the anatomy. The
position of the trackers 16 relative to the anatomy to which they
are attached can be determined by registration techniques, such as
point-based registration in which a digitizing probe P (e.g.,
navigation pointer) is used to touch off on bony landmarks on the
bone or to touch on several points on the bone for surface-based
registration. Conventional registration techniques can be employed
to correlate the pose of the trackers 16 to the patient's anatomy,
e.g., the bones being treated.
[0038] A base tracker 16 is also coupled to the base 22 to track
the pose of the cutting tool 30, e.g., when combined with data
derived from joint encoders in the joints of the robotic arm 20
that partially define the spatial transformation from the base 22
to the distal end 28 of the robotic arm, and when combined with
data describing the location of the cutting tool 30 with respect to
the distal end 28. In other embodiments, a separate tracker 16
could be fixed to the cutting tool 30, e.g., integrated into the
cutting tool 30 during manufacture or may be separately mounted to
the cutting tool 30 in preparation for the surgical procedure. In
any case, a working end of the cutting tool 30 is being tracked by
virtue of the base tracker 16 or other tracker. The working end may
be a distal end of an accessory of the cutting tool 30. Such
accessories may comprise a saw blade 50, such as an oscillating saw
blade.
[0039] In the illustrated embodiment, the trackers 16 are passive
trackers. In this embodiment, each tracker 16 has at least three
passive tracking elements or markers M for reflecting light from
the localizer 14 back to the optical sensors. In other embodiments,
the trackers 16 are active trackers and may have light emitting
diodes or LEDs transmitting light, such as infrared light to the
optical sensors. Based on the received optical signals, navigation
controller 36 generates data indicating the relative positions and
orientations of the trackers 16 relative to the localizer 14. In
some cases, more or fewer markers may be employed. For instance, in
cases in which the object being tracked is rotatable about a line,
two markers can be used to determine an orientation of the line by
measuring positions of the markers at various locations about the
line. It should be appreciated that the localizer 14 and trackers
16, although described above as utilizing optical tracking
techniques, could alternatively, or additionally, utilize other
tracking modalities to track the objects, such as electromagnetic
tracking, radio frequency tracking, ultrasound tracking, inertial
tracking, combinations thereof, and the like.
[0040] In some embodiments, such as the embodiment illustrated in
FIG. 2, the cutting tool 30 includes a coupler 40 having a housing
42 for attaching to the robotic manipulator. It is also
contemplated that a separate motor 44 may be located in the housing
42 of the coupler 40. The motor 44 may be of any suitable type to
operate the cutting tool 30, including but not limited to a
pneumatic or electrical motor. The motor 44 is configured, for
instance, to provide oscillating motion to the saw blade 50 of the
cutting tool 30 during the surgical procedure. It is contemplated
that the motor 44 may provide cyclical linear motion and/or
cyclical angular motion, such as used for an oscillating sagittal
saw. In some embodiments, the cutting tool 30 may include a drive
hub 46 coupled to the motor 44.
[0041] The saw blade 50 may be of any size, shape, or type (i.e.
straight blade, crescent blade, etc.). The saw blade 50 includes an
attachment portion 52 configured to be removably coupled to the
housing 42. Opposite the attachment portion 52, the saw blade 50
includes a cutting portion 54 which has a plurality of teeth 56. In
some embodiments, the saw blade 50 is formed from a single piece of
material, such as metal, by stamping and/or machining. The saw
blade 50 may be configured to create a kerf with a generally flat
face or may be configured to provide a kerf with a rounded profile.
However, various configurations have been contemplated. The cutting
tool 30 and associated saw blade 50 may be like that described in
U.S. Patent Application Pub. No. 2017/0348007, filed on Jun. 2,
2017, entitled "Surgical Saw and Saw Blade for use therewith,"
which is hereby incorporated herein by reference. The cutting tool
30 and associated saw blade 50 may also be like that described in
U.S. Patent Application Pub. No. 2014/0180290, filed on Dec. 21,
2012, entitled "Systems and Methods for Haptic Control of a
Surgical Tool," which is hereby incorporated herein by
reference.
[0042] Referring now to FIGS. 3A through 7B, a desired cutting
plane 66 is defined as the plane in which a planar cut is desired
to be made with the saw blade 50. In the embodiments illustrated,
the cutting plane 66 is disposed transverse to an outer surface of
the hard tissue 12. More specifically, the outer surface of the
hard tissue 12 (e.g., bone) is arcuate or curved such that the
cutting plane 66 often extends non-perpendicularly from the outer
surface. As a result, merely placing the saw blade 50 on the
cutting plane 66, starting oscillation of the saw blade 50, and
then making contact with the outer surface to initiate cutting,
without more, will likely result in skiving of the saw blade 50
along the curved outer surface. The systems and methods described
herein are intended to limit such skiving.
[0043] In these systems and methods, virtual objects (such as
virtual boundaries), which may also be haptic objects (such as
haptic boundaries), may be used to control (e.g., limit and/or
constrain) movement of the saw blade 50 by operating the robotic
arm in a desired manner to limit skiving. These virtual/haptic
objects may be defined by points, lines, planes, volumes, or the
like, and may be 1-D, 2-D, or 3-D. Such virtual/haptic objects may
be defined as models and could be solid models (e.g., built with
constructive solid geometry or the like), surface models (e.g.,
surface mesh, etc.), or any suitable form of 3-D model. These
objects may be registered pre-operatively or intraoperatively to
images/models (e.g., CT scans, X-ray images, MRI images, 3-D
models, etc.) of the patient's anatomy that are mapped to the
patient's actual anatomy using well-known registration techniques.
Thus, in some embodiments, the locations of the virtual/haptic
objects described herein are mapped to the patient's anatomy to
control movement of the saw blade 50 in a manner that limits
skiving of the saw blade 50. For example, the robotic cutting
system 10 may be controlled based on a haptic boundary that defines
a desired plane in which the saw blade 50 should be constrained. In
this case, the robotic controller 32 operates the robotic arm 20 so
that the saw blade is confined by the haptic boundary to stay on
the desired plane. The manner of controlling the robotic cutting
system, e.g., the robotic arm 20, based on such virtual/haptic
objects is described, for example, in U.S. Pat. Nos. 8,010,180,
9,119,655, or U.S. Patent Application Pub. No. 2014/0180290, all of
which are hereby incorporated herein by reference.
[0044] In some procedures, such as during a total knee procedure,
several planar cuts are made to the hard tissue 12, and any of
these planar cuts may employ the methods described herein. In some
embodiments, cutting may be completely through the hard tissue 12
or only partially through the hard tissue 12 such that the cut is
finished when a pre-determined final depth is reached. The cutting
plane 66 may be defined pre-operatively by the surgeon, such as by
defining desired planar cuts on a virtual 3-D model of the hard
tissue 12 created using pre-operative images taken of the hard
tissue. The desired planar cuts may also be defined by the shape of
the implant and a 3-D model of the implant. The cutting plane 66
may be defined intraoperatively by the surgeon, or automatically by
the control system. A position and orientation of the cutting plane
66 may be tracked by the navigation system 13 as the hard tissue 12
moves during the surgical procedure by virtue of the tracker 16
attached to the hard tissue 12 and registration of the tracker 16
to the hard tissue 12. The location of the cutting plane 66 may be
tracked by virtue of being mapped to the 3-D model that includes
the cutting plane 66. The robotic manipulator can accommodate
movement of the cutting plane 66 and autonomously adjust its own
positioning as needed to maintain any desired relationship to the
hard tissue 12 required in the methods described herein, such as
staying on a desired plane with respect to the hard tissue 12 when
necessary. Such control may be accomplished using the robotic
controls described, for example, in U.S. Patent No. 8,010,180, U.S.
Patent No. 9,119,655, or U.S. Patent Application Pub. No.
2014/0180290, all of which are hereby incorporated herein by
reference.
[0045] Referring to FIGS. 3A and 3B, one system and method for
limiting skiving of the saw blade 50 is illustrated. In this
embodiment, the robotic cutting system 10 begins the cut with the
saw blade 50 in a first orientation 70 which is normal to the outer
surface of the hard tissue 12 in the vicinity of the cutting plane
66. The saw blade 50 remains in the first orientation 70 until the
cut reaches a predetermined depth. It is also contemplated that the
first orientation 70 may be any position not in-line with the
cutting plane 66 that provides an advantage in reducing skiving of
the saw blade 50. The predetermined depth may be any depth, but is
typically enough depth to create an initial notch 60 (also referred
to as a groove) in the hard tissue 12. Once the notch 60 is
created, the saw blade 50 is reoriented (e.g., articulated) to a
second orientation 72 (see FIG. 3B), in line with the cutting plane
66, and the cut is finished. The notch 60 is used to create a
fulcrum in the hard tissue 12 about which the saw blade 50 is able
to pivot from the first orientation 70 to the second orientation
72.
[0046] In operation, the cutting tool 30 is first coupled to the
robotic manipulator. The control system is configured to control
movement of the cutting tool 30 via the robotic manipulator. The
control system may comprise a tool controller for operating the
motor 44 of the cutting tool 30 to facilitate cutting. The tool
controller may comprise part of the robotic controller 32, or be
separate from the robotic controller 32. When the cutting tool 30
is coupled to the robotic manipulator, and the user is ready to
begin cutting along the cutting plane 66, the control system will
send a command to the robotic arm 20 (e.g., to control the joint
motors thereof) to move the cutting tool 30 so that the saw blade
50 is first located on (e.g., aligned with) an initial plane
associated with the first orientation 70 (FIG. 3A). The saw blade
50 is aligned with the initial plane by being in the same general
orientation as the initial plane with the initial plane passing
through or being adjacent to the saw blade 50. In other
embodiments, the user may position the cutting tool 30 at the first
orientation 70 by virtue of haptic guidance as described herein.
The user may be able to operate the robotic cutting system 10 to
move the cutting tool 30 so that the saw blade 50 is automatically
aligned with the initial plane in the first orientation in the
manner described in U.S. Patent Application Pub. No. 2014/0180290,
which is incorporated herein by reference. The robotic cutting
system 10, by virtue of the navigation system 13 and associated
trackers 16, and/or by virtue of the encoders in the joints of the
robotic arm 20, is able to determine the position and orientation
of the saw blade 50 with respect to the initial plane to locate the
saw blade 50 as required. In some versions, the initial plane
passes through an intersection of the cutting plane 66 and the
outer surface of the hard tissue 12, but is normal to the outer
surface of the hard tissue 12 at the intersection. Accordingly, by
orienting the saw blade 50 generally normal to the outer surface of
the hard tissue 12, skiving can be limited during cutting. A
current position of the saw blade 50 and/or the desired position of
the saw blade 50 relative to the patient's anatomy may be
represented on a display and updated in real-time so that the user
is able to visualize when the saw blade 50 is in the desired
position (e.g. in the first orientation on the initial plane).
[0047] Once at the first orientation 70, the control system then
operates the motor 44 to start oscillating the saw blade 50 to
begin the initial cut to the outer surface of the hard tissue 12.
The control system may automatically start oscillation, or this may
be in response to user input (e.g., a trigger). The saw blade 50 is
then moved along the initial plane toward the hard tissue 12 to
form the notch 60. Movement of the cutting tool 30 toward the hard
tissue 12 to make the initial cut can be done autonomously or
manually. One or more virtual boundaries (e.g., a virtual plane)
may be activated to define the first orientation 70 to keep the
cutting tool 30 on the initial plane associated with the first
orientation 70 and to prevent the user from cutting beyond the
initial notch 60 that is needed (e.g., the virtual boundary may be
limited in depth). The same virtual boundaries can also be used to
provide haptic guidance to the user to initially locate the saw
blade 50 on the initial plane associated with the first orientation
70. For example, a virtual boundary (e.g., virtual plane) with a
width only slightly larger than the saw blade 50 (to accommodate
for oscillations) and a depth at the depth of the initial notch 60
may be programmed into the control system so that any attempt by
the user to manually move the saw blade 50 outside of the boundary
(e.g., off the plane and/or deeper than the initial notch 60)
results in haptic feedback from the robotic manipulator in the same
manner described in U.S. Pat. No. 8,010,180, incorporated herein by
reference.
[0048] One example of a virtual boundary VB1 to align the saw blade
50 with the initial plane is shown in FIG. 3A in the form of a
bounded volume that defines the initial plane. The virtual boundary
VB1 has a thickness about the thickness of the saw blade 50 to
constrain the saw blade 50 from moving away from the first
orientation 70, a width (not shown) which is about the same as the
width of the saw blade 50 (when oscillating) to avoid any
unnecessary lateral movement, an open starting end (so that the saw
blade 50 can enter the virtual boundary VB1), and a closed target
end at the desired depth of the notch 60. The virtual boundary VB1
can be mapped with respect to the hard tissue 12 pre-operatively or
intra-operatively using registration techniques for mapping the
model of the virtual boundary VB1 to the 3-D model of the hard
tissue 12. Alternatively, the user could locate the virtual
boundary VB1 manually on a user interface connected to the
navigation controller 36. Such virtual boundaries may also be
haptic boundaries that operate to limit or constrain movement of
the saw blade 50 and provide haptic feedback to the user in the
event the saw blade 50 is being moved in a manner that violates, or
will violate, the boundary.
[0049] Once the predetermined depth is reached and the initial
notch 60 is formed, the saw blade 50 is autonomously reoriented by
the robotic manipulator (or manually by the user) to the second
orientation 72 in line with the cutting plane 66, as illustrated in
FIG. 3B. Thus, the virtual boundary VB1 may be deactivated and a
separate virtual boundary associated with the second orientation 72
may be activated to keep the saw blade 50 on the cutting plane 66
during manual cutting. The saw blade 50 then finishes the cut
through the hard tissue 12 along the cutting plane 66.
[0050] It is contemplated that the saw blade 50 may continue
cutting during reorientation from the first orientation 70 to the
second orientation 72 such that the notch 60 has an arcuate shape.
In this case, the teeth of the saw blade 50 may be arranged to cut
the hard tissue 12 in multiple directions, including in the
direction of reorientation to form the notch 60. However, it is
also contemplated that the blade 50 may be removed from the hard
tissue 12 and then reoriented to the second orientation 72 before
finishing the cut along the cutting plane 66--in this case a small
ridge of bone left from cutting along the initial plane may first
be encountered by the saw blade 50 before it reaches the notch 60,
which may cause a slight deflection of the saw blade 50, but then
the notch 60 acts to capture the saw blade 50 and keep it on the
cutting plane 66.
[0051] To facilitate movement from the first orientation 70 and the
initial plane to the second orientation 72 and the cutting plane
66, an intermediate virtual boundary may be provided that extends
from the initial plane to the cutting plane so that the user in
unable to move the saw blade 50 beyond either plane, but is allowed
to freely reorient the saw blade 50 manually. In one version, the
distal end of the saw blade 50 pivots in the notch 60 from the
first orientation and the initial plane to the second orientation
and the cutting plane. The robotic cutting system 10 may also
operate to automatically move the saw blade 50 from the initial
plane to the cutting plane 66 in the same manner that the control
system in U.S. Patent Application Pub. No. 2014/0180290, which is
incorporated herein by reference, automatically aligns the saw
blade. Thus, such motion may be manual or autonomous. Another
virtual boundary may be activated once the saw blade 50 is aligned
with the cutting plane 66 to restrict movement of the saw blade 50
to along the cutting plane 66. This virtual boundary may also be a
haptic boundary that limits or constrains movement of the saw blade
50 to the cutting plane 66. An example of this virtual boundary is
illustrated as virtual boundary VB2 in FIG. 3B, which is shown as a
volume, similar to the virtual boundary VB1.
[0052] In another embodiment, illustrated in FIG. 4, the cutting
tool 30 is initially placed in line with the cutting plane 66
(either autonomously or manually with virtual objects). For
instance, the user may be able to operate the robotic cutting
system 10 to move the cutting tool 30 so that the saw blade 50 is
automatically aligned with the cutting plane 66 in the manner
described in U.S. Patent Application Pub. No. 2014/0180290, which
is incorporated herein by reference. Once on the cutting plane 66,
the cutting tool 30 is reciprocated to form the initial notch 60 in
the hard tissue 12. This reciprocating motion (also referred to as
pecking) may be carried out autonomously or manually as well. This
reciprocating motion may be defined as motion axially along a
longitudinal axis of the blade, e.g., reciprocating lengthwise. If
carried out autonomously, the robotic manipulator is configured to
move the cutting tool 30 and its saw blade 50 along the cutting
plane 66 at incrementally increasing depth, in combination with
slight retractions, to effectively chip away at the outer surface
of the hard tissue 12 to limit skiving that could otherwise occur
if attempting to start cutting at a non-perpendicular orientation
to the curved surface. In this case, the autonomous movement
creates the reciprocating motion needed to form the initial notch
60 in the hard tissue 12 such that the saw blade 50 is capable of
being captured in the notch to limit skiving. The saw blade 50 may
be constrained to stay on the cutting plane 66 via one or more
virtual boundaries associated with each of the reciprocations
(e.g., the virtual boundary dynamically changes to increase the
depth as hard tissue is removed, or new virtual boundaries are
created after each contact made with the hard tissue 12). An
example of an initial virtual boundary VB3 for the first peck at
the hard tissue 12 and sequentially created virtual boundaries VB4,
VBS, VB6 for subsequent pecks at the hard tissue 12 are shown in
FIG. 4. Once the initial peck is made with the robotic cutting
system 10 using the virtual boundary VB3, then virtual boundary VB3
is deactivated and virtual boundary VB4 is activated to penetrate
into the hard tissue 12 slightly further, and so on, until the
notch 60 is formed.
[0053] In some versions, the reciprocation is carried out by
actuating the joint motors of the robotic manipulator in a manner
that causes the saw blade 50 to reciprocate. This can be
accomplished by activating the joint motors so that the saw blade
50 remains aligned with the cutting plane 66, yet translates along
the cutting plane 66 back and forth a desired distance and at a
desired frequency. In other versions, the cutting tool 30 has a
reciprocating feature to reciprocate the saw blade 50 along its
cutting plane. In this version, the robotic manipulator merely
places the distal end of the saw blade 66 at an interface with the
outer surface of the hard tissue 12 on the cutting plane 66 and the
tool controller then activates the cutting tool 30 to begin its
reciprocating motion to peck the hard tissue 12 and form the notch
60.
[0054] Ultimately, during reciprocation, the saw blade 50
repeatedly contacts the hard tissue 12 with repeating force to form
the initial notch 60 at the predetermined depth. In other words,
the saw blade 50 pecks at the hard tissue 12 using the force to
produce the notch 60. Two, three, four, or more sequential
reciprocations may be needed to form the initial notch 60 in the
bone. The robotic controller 32 may control the robotic manipulator
so that the reciprocations may be conducted at frequencies of one
reciprocation every second, one every millisecond, or the like. The
duration, frequency, and depth of such reciprocations (including
distance of retracting away from the hard tissue 12) may vary as
needed to create the initial notch 60. Forces could also be
monitored during such reciprocations so that the force applied on
the hard tissue 12 by the robotic manipulator during pecking is
kept at or below certain thresholds. In some embodiments, the saw
blade 50 is oscillating during the reciprocation. Once the
predetermined depth is reached, the control system is configured to
continue oscillation of the saw blade 50 and control the saw blade
50 to finish the cut along the cutting plane 66 as previously
described, e.g., without reciprocating, such as to resect a portion
of the bone. In other embodiments, the reciprocating motion is
carried out while the saw blade 50 is stationary with respect to
the housing 42, e.g., the saw blade 50 is not oscillating.
[0055] Additionally, the oscillating speed of the blade tip (which
oscillates laterally on the cut plane), in some cases decreases,
increases or otherwise varies during the creation of the notch, or
during the pecking motion. This reduces the lateral reaction forces
exerted on the bone, until the blade is sufficiently
captured/constrained inside the bone by the bone material. The
control system is configured to control and vary the oscillating
speed in any desired manner, including automatically varying the
speed according to a predetermined speed profile. For example, the
oscillating speed may start at an initial speed much slower than a
normal oscillating speed, and then increase a predetermined
percentage (e.g., 5% or more, 10% or more, 20% or more, 50% or
more, etc.) for every subsequent peck or reciprocation until at
normal oscillating speed. Other speed profiles may be used.
[0056] In another exemplary embodiment, illustrated in FIGS. 5A and
5B, another cutting tool 30 may be used to form the initial notch
60 to limit skiving of the saw blade 50. In this case, the cutting
tool 30 comprises a bur 62. The cutting tool 30 with the bur 62 may
be initially connected to the robotic manipulator and configured to
cut the hard tissue 12 until the cut reaches the desired depth to
form the notch 60. The cut with the bur 62 can be carried out
autonomously or manually in the manner previously described.
[0057] The bur 62 is used by the robotic cutting system 10 to
create a desired profile in the hard tissue 12 to enable easier
initial cutting of the saw blade 50 into the hard tissue 12 along
the cutting plane 66. In the embodiment shown, the notch 60 is
formed by the bur 62 to have a profile that both creates a face of
hard tissue that's easier for the saw blade 50 to initially cut
without skiving and creates a plateau to guide and support the saw
blade 50 on the cutting plane 66 (see FIG. 5B). As illustrated in
FIG. 5A, the bur 62 may be cylindrical such that the bur 62 forms
the desired notch 60 in the hard tissue 12 when rotating about a
rotational axis perpendicular to the cutting plane 66, e.g., an
axis transverse to the cutting plane 66. Additionally, it is also
contemplated, that the bur 62 may be spherical such that the bur 62
forms a rounded notch in the hard tissue 12 with the notch being
concave in the outer surface to readily capture the saw blade 50
and prevent skiving by constraining the saw blade 50 from flexing.
Various other bur configurations have been contemplated.
[0058] Once the notch 60 is formed, the robotic cutting system 10
will then finish the cut using the saw blade 50 in the same manner
previously described. It is contemplated that the cutting tool 30
comprising the bur 62 may be uncoupled from the robotic manipulator
once the notch 60 is formed so that the cutting tool 30 with the
saw blade 50 can be fitted to the robotic manipulator. However, the
cutting tool 30 with the bur 62 may remain coupled to the robotic
manipulator in cases where two end effectors are capable of being
attached to the robotic manipulator simultaneously. It is also
contemplated that the cutting tool 30 is capable of receiving both
the bur 62 and the saw blade 50 interchangeably so that only the
bur 62 needs to be removed and the saw blade 50 attached. It is
additionally contemplated that the initial cut done by the bur 62
may be performed with a manual cutting instrument without being
connected to the robotic manipulator.
[0059] Referring to FIGS. 6A and 6B, the cutting portion 54 of the
saw blade 50 may include a rounded tip 58 configured to engage the
hard tissue 12. The rounded tip 58 is configured to create a
rounded notch 60 in the hard tissue 12 during the cutting
operation. The rounded notch 60 provides a starting point for the
saw blade 50 to more easily complete the remainder of the cut along
the cutting plane 66 by establishing a fulcrum about which the saw
blade 50 can be reoriented to the cutting plane 66. Similar to the
embodiment illustrated in FIGS. 3A and 3B, the cutting tool 30
begins the cut with the saw blade 50 in the first orientation 70
(FIG. 6A) which is normal to the outer surface of the hard tissue
12. The saw blade 50 remains in the first orientation 70 until the
cut reaches a predetermined depth. Once the notch 60 is created,
the saw blade 50 is rotated to the second orientation 72 (FIG. 6B),
in line with the cutting plane 66, and the cut is finished. As
shown in FIG. 6B, the saw blade 50 may be removed from the notch 60
before completing the final cut or the saw blade 50 may remain in
the notch 60.
[0060] In another exemplary embodiment, illustrated in FIGS. 7A and
7B, the robotic cutting system 10 further includes a rigid blade
guide 74. The blade guide 74 is coupled to the housing 42 and is
configured to provide support to the saw blade 50 during operation
of the robotic cutting system 10. More specifically, the blade
guide 74 has a rigidity which can provide stability to the saw
blade 50 and withstand transverse forces from the hard tissue 12
acting on the saw blade 50 during operation that may otherwise
cause skiving. Additionally, use of the blade guide 74 allows a
thinner saw blade 50 to be used owing to the additional support
being given to the saw blade 50 by the blade guide 74.
[0061] In the embodiment illustrated in FIGS. 7A and 7B, the blade
guide 74 is a telescoping blade guide 74. More specifically, the
blade guide 74 is configured to move between an extended position
76 (FIG. 7A) and a retracted position 78 (FIG. 7B). As illustrated
in FIG. 7A, the blade guide 74 may include a first end 80 which is
configured to receive the saw blade 50 of the cutting tool 30. It
is contemplated that the first end 80 of the blade guide 74 may
provide a passage sized to receive the saw blade 50 in a sliding
manner such that the saw blade 50 is neatly disposed between and
constrained from flexing by upper and lower walls of the blade
guide 74, but is allowed to slide/oscillate within the blade guide
74 (see FIG. 7C). It is also contemplated that the blade guide 74
may engage the saw blade 50 in any manner configured to provide
support and rigidity to the saw blade 50.
[0062] During operation, the blade guide 74 moves between the
extended position 76 and the retracted position 78. In other words,
at least a portion of the blade guide 74 may have telescoping
members 82 configured to extend/retract the blade guide 74.
Movement of the blade guide 74 may be controlled by the control
system of the robotic cutting system 10. For example, an actuator A
(e.g., electric motor) may be coupled to the telescoping members 82
or directly to the blade guide 74 to extend/retract the blade guide
74 (see FIG. 7B). For example, an electric linear actuator may be
mounted to the housing 42 with an extendable rod connected to the
blade guide 74 to extend/retract the blade guide 74. It is also
contemplated that the blade guide 74 may be manually operated. In
one embodiment (see FIG. 7A), the blade guide 74 includes a biasing
device (e.g., springs S) which spring bias the blade guide 74
towards the extended position 76. The biasing device is arranged so
that when the blade guide 74 engages the hard tissue 12 and the saw
blade 50 is further driven into the hard tissue 12, the blade guide
74 retracts, albeit while continuously being biased toward the hard
tissue 12 by the biasing device.
[0063] When cutting along the cutting plane 66 is desired, the
cutting tool 30 is first aligned with the cutting plane 66 in the
manner previously described with the blade guide supporting the saw
blade 50 in the extended position 76. The saw blade 50 is then
moved (either manually or autonomously as previously described) to
engage the hard tissue 12 to begin the cut. During the cut, the
blade guide 74 provides support to the saw blade 50. Moreover, as
the saw blade 50 enters the hard tissue 12, the blade guide 74
telescopes from the extended position 76 (illustrated in FIG. 7A)
to the retracted position 78 (illustrated in FIG. 7B) such that the
blade guide 74 remains outside of the hard tissue 12 as the saw
blade 50 enters deeper into the hard tissue 12. In the case of
using an actuator to move the blade guide 74, the navigation system
13 monitors movement of the saw blade 50 relative to the hard
tissue 12 and the control system operates the actuator A as desired
to move the blade guide 74 in a coordinated manner so that the saw
blade 50 is continuously supported during at least the initial cut
into the hard tissue 12 adjacent to the outer surface. The saw
blade 50 finally finishes the cut along the cutting plane 66.
[0064] Several embodiments have been discussed in the foregoing
description. However, the embodiments discussed herein are not
intended to be exhaustive or limit the invention to any particular
form. The terminology which has been used is intended to be in the
nature of words of description rather than of limitation. Many
modifications and variations are possible in light of the above
teachings and the invention may be practiced otherwise than as
specifically described.
* * * * *